1. Field of the Invention
The present invention relates to an image tracking device, an imaging device, an image tracking method, and an imaging method.
2. Description of Related Art
The following type of auto focus system is known. In this auto focus system, there are provided an automatic focus adjustment (AF) function with which the defocus amounts of a photographic lens are obtained for a plurality of focus detection areas that are set within its photographic scene, and focus adjustment of the photographic lens is performed based upon the defocus amount of any one of these areas, and an image tracking function with which an image of a photographic subject within the photographed image that is to be the subject of tracking is stored as a template image (i.e. as a reference image), and then the photographic subject is tracked while searching, within images that are repeatedly captured, for positions in the images that are the same as, or that resemble, the template image. And a focus detection area is selected that corresponds to the position of the image tracking result, and the focal state of the photographic lens is adjusted according to the defocus amount of that focus detection area. (See Japanese Laid-Open Patent Publication No. 2005-215040.)
With the above described prior art auto focus system, it is not possible to start the focus detection calculation until the image information that is needed for calculation for tracking the photographic subject is obtained, since the focus detection calculation for the photographic lens is performed based upon the tracking calculation result for the photographic subject. Accordingly if the calculation processing time period for each photograph is limited, as for example during sequential shooting or the like, then it is not possible to perform efficient control within this limited calculation processing time period.